Diesel fuel, particularly No. 2 fuel oil, has the tendency to gel or "wax" in cold weather. This gelling of diesel fuel is a particularly acute problem in the trucking industry during colder months in portions of the U.S., Canada, and Europe. During the winter months, temperatures and wind chill factors frequently reach minus 30.degree. Fahrenheit in these areas. In such a temperature and windchill range, diesel fuel tends to gel or wax both in the fuel tank itself and within a fuel line leading from the tank to the engine. In the severest instances of gelling, the diesel engine completely fails. The truck or other vehicle thus must be towed to a service area and the fuel system heated. The towing and down time of the truck results in increased transportation cost. In less severe instances, the gelling can result in loss of power so that the trucks are forced to travel at a slow rate of speed. This also results in increased transportation cost.
Similar cold weather problems exist with the use of hydraulic oil. Typically, hydraulic oils of various grades experience viscosity changes dependent on temperature. In cold weather or winter months, hydraulic oil which is cold provides slower response times to the equipment it is powering. Moreover, cold hydraulic oil may cause: pump damage from cavitation; slower operation from hydraulic motors; high pressure leaks; blown hose ends; blown seals; and other problems. Often it is necessary to warm the hydraulic oil reservoir prior to powered operation of equipment to avoid improper operation.
Problems also exist when diesel fuel or hydraulic oil is warmer than an optimum operating range. In the case of diesel fuel, optimal operating temperatures may range generally between about 60.degree. F. and about 110.degree. F., subject to quality of the diesel fuel, additives therein, and other considerations. Frequently, diesel fuel in trucks and vehicles operating in warmer climates or for long durations produce heating effects within the engines that cause the fuel temperature to exceed the optimum power ranges. This overheating may result in numerous problems, including damage to electronic components in engine systems. Therefore, it is desirable to reduce the amount of heat in the fuel in such situations. Similarly, when hydraulic oil is warmed beyond an optimum range, power control problems and residual heating effects may occur. It is therefore desirable to reduce the amount of heat in hydraulic oil reservoirs when the temperature of such reservoirs exceeds a predetermined range.
Numerous methods and apparatus have been used in the past in an attempt to solve these or related problems. A temperature controlling system for use with a fluid cooled internal combustion engine of an automotive transport system, during periods when the combustion engine is not in operation, is provided in U.S. Pat. No. 4,286,551 issued to James E. Blitz on Sept. 1, 1981. The device disclosed in the Blitz patent includes a manually operated three-way cut-off valve and bypass conduit means permitting fluid coolant to be optionally diverted from passage through the internal combustion engine, heated and pumped in response to a power source and temperature sensing means through pipe coils and conduit means located in relation to an automotive transport diesel storage vessel or automotive transport hydraulic unit storage vessel.
Another method is disclosed in U.S. Pat. No. 4,237,850 issued to Frank G. Connor and Billy B. R. Veach on Dec. 9, 1980. The Connor et al "System for Heating Fuel Oil" patent is substantially similar to portions of, and is owned by, the assignee of the present applicants. However, the device disclosed in the Connor et al patent is substantially improved with addition of the manifold device disclosed in the present application to selectively bypass heat exchange medium from flowing through the heat exchange conduits of the Connor device. Moreover, a manifold device in cooperation with the Connor device permits heating, cooling, or bypassing of the heat exchange conduits.
A diesel fuel temperature controlling apparatus is also disclosed in U.S. Pat. No. 4,393,851 issued to Marc S. Gorans. The Gorans patent includes a thermostatic valve means for modulating the flow of diesel fuel through passageways in response to temperature of unmixed and unheated bypassed fuel. Similarly, a valve controlled fuel heater with self-adjusting valves is disclosed in U.S. Pat. No. 4,434,773 issued to Dennis C. Granstake, in which a temperature responsive valve body is movable between a first extreme position for directing fuel through a path of heat receiving relationship with a heater means when the fuel temperature is cold, and a second extreme position that directs the fuel to bypass the heater means when the fuel is hot.
In many of these prior systems, disadvantages exist. For example, most systems do not provide temperature sensing means which are placed directly into a fuel or oil reservoir tank bottom and therefore do not accurately sense a temperature of fuel or oil therein. Further, many prior art systems provide means for bypassing flow of fuel in response to various pressure/temperature sensing means rather than improved regulation of a heat exchange medium flow. Moreover, prior art systems do not typically permit continuous flow heat exchange loops during all phases of operation of a vehicle, truck, or other equipment in which the system is functioning. A continuous flow loop during all phases of operation is particularly desirable in cooperation with preheating or precooling devices, as well as pumping means.
Frequently, fuel and oil heating devices do not adequately safeguard electronic components now more prevalent within the control systems of engines. This in itself creates various problems. Overheating of electronic components in engine control systems often results in failure of those components. A secondary effect of failure of engine control components may be substantial damage to the engine, or at least a significant degradation in engine operation.
Other disadvantages of present day diesel fuel and hydraulic oil temperature control devices include: electrical components which may cause significant maintenance problems; valves which must be manually operated to effect bypass conditions; inefficient placement of heat exchange conduits in relation to the diesel fuel and/or hydraulic oil; difficulty in installation; and, numerous components requiring substantial supply and repair concerns. Other present day systems do not provide devices which may be configured for either heating or cooling purposes using virtually interchangeable parts, while other systems are not optimally located on the top portions of diesel fuel and/or hydraulic oil reservoirs. In such systems, adaptability to operation in various climates is often impractical.
What has been needed has been an improved system for bypassing heat exchange medium flow: providing an easily installed and readily adaptable system for warm weather or cold weather operations; providing means for temperature sensing of diesel fuel or hydraulic oil actually within the respective reservoirs; providing for continuous loop heat exchange medium flow when the system is in a bypassed mode; providing means for warming or cooling fuel oil when that oil is being drawn into a fuel line from a diesel fuel reservoir; providing a non-electrical, completely mechanical actuator means for operating the manifold device, thereby permitting more reliable operation. Also, a diesel fuel and hydraulic oil reservoir heating and cooling system which is relatively inexpensive to manufacture and is easily installed is preferred.
Objects and advantages of the present invention in achieving these and other goals will become apparent from the following descriptions, taken in connection with the accompanying drawings, wherein are set forth by way of illustration and example certain embodiments of the present invention.